i always felt if they were to continue the series on film that, present day might be the way to go. 20-25 years after Vincent takes over, hell maybe even from when michael Dies(what year was that? 92?) Anyways have that be the begining, and then Focus on the fall of the Corleones. have the movie focus not so much on Vincent, but on a Capo, or just buttonman, and his everyday struggles in the most famous mafia family in the world. i think A story kline that ends the saga would give some closure. and that opens things up for any flashback that seems to be the running theme here.